HP Surestore Tape Library Model 6/60 SAN Solution Installation Guide - Page 15

Topologies and Components Components Components Cabling While the SAN supports a number of interfaces, Fibre Channel (FC) and FC fabrics have gained attention due to flexibility, high throughput, inherent fault-tolerant access paths, and the potential for revitalizing network-to-storage communications. Components can be connected either by copper or fiber-optic cabling. Each cable type has definite advantages and disadvantages when used within a SAN. • Copper is less expensive, but is less reliable and has limited distance considerations. • Fiber-optic is more expensive, easier to use, more reliable and can be utilized in distances up to 10km. Fibre Channel Components/Plug-In Modules Each device connected to a fabric requires an interface or adapter board. Boards will have an integrated component or a plug-in module. Two module types are: • GigaBit Interface Converter (GBIC) - a removable transceiver module for FC and Gigabit Ethernet physical-layer transport. • Gigabaud Link Modules (GLMs) - a semi-permanent transceiver that incorporates serializing/deserializing functions. Hubs Fibre Channel hubs establish connectivity for arbitrated loops. An Arbitrated Loop (AL) allows up to 127 devices to share the same 1Gbps bandwidth. The disadvantage of AL is that only two devices will be active at any given time. The advantage of AL is that Port Bypass Capability enables hubs to deactivate bad ports. • Hub - in FC, a wiring concentrator that collapses a loop topology into a physical star topology. Chapter 1 1-5